Cellulose fiber pulp sheet impregnated with a long chain cationic debonding agent

ABSTRACT

A PULP SHEET IMPREGNATED WITH ABOUT 0.25% TO 1.0%, AND PREFERABLY ABOUT 0.25% TO 0.5%, BASED ON THE WEIGHT OF THE DRY PULP, OF A CATIONIC LONG CHAIN FATTY ALKYL COMPOUND DEBONDING AGENT HAVING AT LEAST 12 CARBON ATOMS IN AT LEAST ONE ALKYL CHAIN SUCH AS DI-HYDROGENATED DIMETHYL AMMONIUM CHLORIDE DERIVED FROM A TALLOW OIL, AND DRYING THE IMPREGNATED PULP TO FORM A PULP SHEET THAT CAN BE EASILY MECHANICALLY FIBERIZED.

United States PatentO 3,554,863 PULP SHEET IMPREGNATED CHAIN CATIONICDEBONDING U.S. Cl. 162158 g 4 Claims ABSTRACT OF THE DISCLOSURE A pulpsheet impregnated with about 0.25% to 1.0%, and preferably about 0.25 to0.5%, based on the weight of the dry pulp, of a cationic long chainfatty alkyl compound debonding agent having at least 12 carbon atoms inat least one alkyl chain such as di-hydrogenated dimethyl ammoniumchloride derived from a tallow oil, and drying the impregnated pulp toform a pulp sheet that can be easily mechanically fiberized.

This application is a continuation-in-part of our application Ser. No.739,641, filed June 25, 1968.

In accordance with this invention, it has been discovered that a pulpsheet formed on a conventional paper machine of the cylinder orFourdrinier type and which sheet is normally diflEicult t fiberize, maybe rendered exceedingly easy to fiberize (by mechanical action) if thepulp sheet or furnish for same is impregnated with critical amounts ofcertain .types of chemical compounds, discussed below. We have foundthat these particular types of chemicals when used in suitable amounts,are unusually and markedly effective in debonding the pulp or pulpsheets treated therewith such that when the pulp sheet is dried andsubjected to mechanical abrasive action, the fibers composing the sheetwill substantially completely separate and produce a very flulfy fibrousmaterial. The loftiness of this material is 33 /s% or higher than thesame type of material which has not been chemically treated before beingsubjected to the fiberizing operation.

It appears that the selected highly effective chemicals function toeliminate or break down the usual bond that exists between the fibersand thereby act as a debonding agent. The evidence of this debondingeffect is shown by, the tensile strength of the treated pulp sheet whichis only about one-third to one-fourth of the tensile strength of thesame sheet untreated. For example, the treated sheet may typically havea tensile strength of about 2 pounds per inch for a sheet having a basisweight of 80 pounds per 3000 square feet in contrast to the untreatedsheet which will typically have a tensile strength of 6 to 8 pounds persquare inch,

The chemicals which we have found effective for obtaining this markedlylower tensile strength of the pulp sheet, comparable ease of debondingby mechanical action and comparable increase in loftiness of thefiberized material, may be generically classified as cationic long chainfatty alkyl compounds having at least 12 carbon atoms in at least onealkyl chain. One of the important characteristics of these compounds istheir cationic nature which attracts them chemically to the anionicfibers. It also appears that the highly eflicient debonding action ofthese chemicals is allied with long chain fatty type chemical compounds.Also, from the standpoint of effective debonding, it is important thatthese chemical compounds have at least 12 carbon atoms in the alkylchain or in at least one of the alkyl chains if a dialkyl type compoundis used.

The effective chemicals may also be classified subgenerically into thefollowing groups, quaternary compounds, tertiary, secondary and primaryamine salts. Some of the quaternary compounds have been found moreadvantageous than some of the amines from the standpoint of lowering thetensile strength of the sheet from the usual 6, 7 or 8 pounds per inchdown to 2 or 3 pounds per inch. However, a number of the primary aminesof the long chain type having about 16, 18 or more carbon atoms haveproven very effective for debonding purposes.

. Illustrative but non-limiting examples of the chemicals in the abovementioned four categories are as follows:

QUATERNARY mono cottonseed oil trimethyl ammonium chloride mono cocotrimethyl ammonium chloride mono stearyl trimethyl ammonium chloridemono oleyl trimethyl ammonium chloride mono soya trimethyl ammoniumchloride dilauryl dimethyl ammonium chloride di hydrogenated dimethylammonium chloride derived from a tallow oil dimethyl ammonium chloridederived from soya oil N-alkyl (C 14, dimethyl benzyl ammonium chloridecoco dimethyl benzyl ammonium chloride TERTIARY mono stearyl dimethylamine chloride SECONDARY di coco amine chloride di hydrogenated tallowamine chloride di oleyl amine chloride PRIMARY dodecylamine chloridepalmitylamine chloride coco amine chloride coco amine acetate stearylamine chloride stearyl amine acetate oleyl amine chloride oleyl amineacetate soya amine chloride tallow amine chloride Any one or more of theselected chemicals above identified may be introduced into the pulp orpulp sheet at a number of different places or steps in commercial pulpsheet forming operations. For example, the chemicals may be added to thepulp slurry contained in a stock chest prior to the paper or paperboardmachine and this is of advantage where it is desired to permit thechemical to remain in contact with the cellulose fibers for some periodof time, e.g., 5-10 minutes, before the slurry is fed to the papermachine. Where prolonged contact with the slurry prior to sheetformation is not necessary or desired, the chemical may be added at thehead box of the paper machine.

Depending upon the type of paper or board making machinery used, thedesired speed of operation, and the desired degree of impregnation ofthe fibers with the chemicals, the chemicals may be introduced into thesheet at the wet press section of the paper machine by suitableconventional equipment, such as a size press or the like. At this point,the chemical will be introduced into the previously formed pulp sheet orboard while it is still relatively wet, and before the sheet or board isfinally dried on the machine.

A suitable type of Fourdrinier paper machine and the process of formingpaper thereon is disclosed in G. L. Bedwell Pat. No. 2,488,700, issuedNov. 22, 1949; and a suitable type of cylinder machine is disclosed inJacob Edge Pat. No. 2,005,839, issued June 25, 1935. And reference maybe had to those patents for disclosures of paper machines and processesof operation suitable for use in the present invention.

The amount of chemical or chemicals to be added to the pulp furnish,slurry, or pulp sheet is important and may vary within the criticalrange specified below, with the type of pulp used and the desired extentof debonding property. The amount should be above .1% by weight based onthe dry pulp. In most cases, the chemicals are highly effective withinthe range of 0.25% to 0.5%. A minute amount of 0.1% may produce somelimited softening of the pulp but an amount of not less than 0.25 isrequired for substantial improvement in fiberizing prop erties. Incommercial practice, employing sulfite process wood pulp, an amount of0.3% to 0.5% of the chemical should be used for best fiberizing results.When using pulp produced by the sulfate process which is harder and moredifiicult to fiberize, the amount of chemical needed may be 0.5% orslightly higher. Amounts of 1% or above are not normally required andalthough they may be used to give some further improvement in fiberizingproperties, the additional chemical cost is usually not justified.

The effectiveness of the chemical treatment of the pulp in accordancewith this invention for rendering the pulp sheet more easily fiberizedis substantially proportional, with a given pulp and a given chemical,to the amount of chemical used within the above range of 0.25% to 0.5 Wehave found, for example, with a sulfite pulp, chemical added in amountof 0.3% based on dry weight of pulp will lower the tensile strength toabout A that of the same pul sheet without the chemical treament. Andthe use of 0.5 of chemical applied to the sulfite pulp will lower thetensile strength to about A that of the same pulp without the chemicaltreatment. This dramatic lowering in tensile strength of the pulp sheetis accompanied by a corresponding improvement in the fiberizingproperties of the pulp sheet such that it fiberizes remarkably easy andproduces the much loftier, cleaner and more uniform long fiber material.

The present invention is applicable to practically all conventionaltypes of pulps made in conventional manner by the well-known kraft,soda, sulfite, or neutral sulfite processes.

The raw material, that is, the fibers to be pulped, impregnated andsheeted in accordance with the present invention, may be any one or moreof the various types of pulp materials commercially used in paper andpaperboard manufacture. Illustrative examples are wood, cotton, linters,flax, hemp, ramie, bagasse, and esparto fiber pulps. Generally speaking,it is desirable to use relatively 4 long fiber material for ultimateindividual fiber strength and for high resistance to breaking, powderingor dusting when subjected to the fiberizing treatment.

After incorporation of the chemicals in the pulp sheet or board at anyof the desired points mentioned above, the formed and impregnated wetsheet is then passed over conventional drying cylinders normally used ina paper machine to provide a fairly dense substantially dried, e.g.,moisture of about 5%l0% by weight, sheet which may typically have athickness of about of an inch, and the dried sheet wound in aconventional manner on rolls for storage or shipment and ultimately forfiberizing by mechanical action to produce the above-described loftyfiuify fiberized material. The final fiuffy material may be used for anydesired purposes such as, for example, in diapers, napkins or othersanitary products, or for bulking or padding purposes, particularlywhere a lofty material is needed. The lofty fiberized properties of thismaterial are also of advantage from the standpoint of efiiciency ofabsorption of body fluids.

Various modifications may be made in the above-described materials,chemicals, process conditions, etc., without departing from the scope ofthis invention as set forth in the appneded claims.

We claim:

1. A cellulose pulp sheet characterized in that the bonding between thefibers is reduced by a surface-active agent, in amount of about 0.25% to1.0% and in the form of a cationic long-chain fatty alkyl compound whichcontains at least 12 carbon atoms in at least one alkyl chain.

2. A cellulose pulp sheet having improved fiberizing properties in whichthe bonding between the fibers is reduced by a surface-active agent, inamount of about 0.3% to 0.5 and in the form of a cationic, long-chainfatty alkyl compound which has at least 12 carbon atoms in at least onealkyl chain, and the tensile strength of the sheet is about /3 to A ofthe normal tensile strength of the same pulp sheet without thesurface-active agent.

3. A cellulose pulp sheet as defined in claim 2 and in which the pulp issulfite pulp.

4. A cellulose pulp sheet, as defined in claim 1, in which the amount ofsurface-active agent is 0.25 to 0.5

References Cited UNITED STATES PATENTS 2,683,087 7/1954 Reynolds 162-l583,395,708 8/1968 Hervey 162179 S. LEON BASHORE, Primary Examiner R. H.ANDERSON, Assistant Examiner US. Cl. X.R.

